The present invention relates to a golf ball which is novel in appearance and excellent in flight performance.
It is known well that a golf ball should have a high rebound resilience and a low aerodynamic resistance during its flight (due to dimples arranged on its surface) if it is to attain a long flying distance after strike. For reduction of aerodynamic resistance, there have been proposed several methods for arranging dimples on the ball surface as densely and uniformly as possible.
Ordinary dimples are round dents as viewed from above. If such round dimples are to be densely arranged, it is necessary to narrow down the flat part (land part) separating adjoining dimples from each other. Even though the flat part is infinitely narrow, there still exists a triangular or rectangular flat part of certain size in the area surrounded by three or four dimples. On the other hand, it is essential to arrange dimples as uniformly as possible on the ball's spherical surface. This necessitates making a compromise between the density and the uniformity of dimple arrangement.
One conventional way to achieve the object of arranging dimples densely and uniformly was to arrange two to five kinds of dimples differing in diameter assuming that the ball's spherical surface is a regular octahedron or icosahedron. (See Japanese Patent Laid-open No. 2001-212260, for example).
However, as far as dimples are round, the total area of dimples practically accounts for only 75% or so in the surface area of the sphere, with the remainder (25%) being the area of flat parts (land parts). For this reason, it has been required to increase the ratio of the total area of dimples accounting for in the total spherical surface area in order to reduce further the aerodynamic resistance during flight due to dimples arranged on the ball surface.